Numerous telescoping spring driven pool cues have been described in the prior art. In most such telescoping pool cues, an inner shaft compresses a spring within a handle. The shaft is latched in a cocked position until released. Spring force drives the shaft forward against an object. A representative example is U.S. Pat. No. 4,134,588 to Di Luzio, which describes a spring actuated short billiard cue stick having a plunger shaft in the bore of a handle member, the shaft being slotted longitudinally in the bore with spaced enlargements therealong, so that a manually releasable latch member that slides along the slot can hold the shaft at a number of retracted positions. U.S. Pat. No. 4,634,123 to Cowan et al. describes a similar device that includes an adjustable stand attached to the front of the device. U.S. Pat. No. 4,718,671 to Desmond et al. describes a spring driven, telescopingly adjustable cue wherein the spring is held at various biases by friction between an inner plunger and a handle within which the inner plunger is encased.
These devices, however, do not offer an easily reproducible means for striking objects, as the force imparted by the shaft varies with the distance the shaft is positioned from the object prior to striking. Since the trajectory of the object also typically varies depending upon the point of impact on the object, the distance the shaft is positioned from the object prior to striking also introduces an angular error in the trajectory, as it makes the point of impact harder to predict.
In pool or billiards, accuracy is mostly a matter of experience. It is difficult to apply a continuously variable amount of force in a reproducible manner time after time, and difficult to strike a ball at the exact point of impact desired. Yet if this could be done, it would allow higher levels of play by less experienced players. It would also facilitate teaching of pool, billiards or similar games.
An object of the invention is to devise a compact pool cue which delivers a continuously variable force in a reproducible manner.